Daily Yellowstone journal., 1887-10-20
THE THEORY OF STORMS.


IN -
How They Originate aud Pass Away.
Sergt. +. h. Dunn, the signal service
officer in charge of the station ON the
Equitable building, thus explained the
theory Of storms the other day:
''Storms are caused he said, first
by the meeting and commingling Of in
equal atmospheric temperatures or pres
sures; second, 10y the rotation of the
earth, and. thirdly, by unequal specific
gravity of different layers of air. The
first of these causes is the prime one; the
other two are but Of secondary and ON
paratively slight importance in the gen.
Grafton of Il storm.
ut is a well known fact that warm air
rises. 1t is equally well known that the
earth becomes heated by the suns rays
falling upon it. and 10y the absorption and
radiation of this stored up heat renders
the temperature higher at the surface
than at elevated points. For a time this
hot air on the surface is kept down by
atmospheric pressure, but there comes a
time when the expansion becomes so
great as TO break through the cold air
Bltroult. anu Aif NV III HNNN UP u a
rush, rising sometimes to great height.
As this warm air rises it createsa vacuum
below, and the cooler air PUSHES in from
all sides 10 fill its place. This cool air, as
it gets gradually heated, also rises, and
more cool air rushes in to again ill the
vacuum. Right at this point where the
hot air first rises IL the center Of a storm.
The vacuum caused by the ascending hot
air sucks into its vortex the air from
every point of the compass, and this sue
ton causes wind, but places affected by
q storm thus formed, it will be seen, will
have the wind from different points Of
the compass, according to their direc-
ton from tie storm center. Thus, a
locality directly south of a storm center
will have the wind from the south, as it
rushes north. When this warm air has
accumulated at q sufficiently high alti-
tude.' and become surrounded by a cooler
air, the moisture in it begins To condense,
forming rain.
1.-The rushing in of the cool air to ell
the vacuum caused by the rising hot air
gives motion to the accumulation Of
warm air. and it begins 10 whirl about
in a circle, bur at the center all is calm
and clear. Thus it is that sometimes we
experience "a lull in the storm as il is
called. Such a brief respite is nothing
more than the passing Of n storm center
directly over head, through which the
sun even may shine mobstructedly.
''As this storm keeps whirling about
over head il continues 10 gather energy.
and grow, by the accession Of more heated
air, exactly as a snowfall is increased in
diameter by rolling it in the snow. At
last the accumulation becomes Of such
proportions as 10 feel the effects of the
earth's rotation, and it begins to move.
This rotation of the earth, being from
west to east, gives all the storms of any
extent the same general direction. Such
general direction. however, from west to
east. is liable TO reflections from various
causes, such as mountains. conditions Of
the atmosphere. by coming in contact
with other storms or air currents. and
by large areas of water.
''Nine out If ten American storms
originate in the mountainous regions Of
the northwest. where the warm air Of
the valleys rises and comes in contact
with the cool air from the great eleva-
tons of the Rocky mountains. These
storms take a generally southeasterly d.
rection until they get into the dry regions
of Kansas. and there, becoming fam
ished. as il were. for want Of moisture,
and as if scenting the water for which
they long from the direction If the great
lake region, they make a turn TO the
northeast and proceed to the great lakes,
where they absorb abundance Of moisture,
and then travel on east, deluging us with
this water from the lakes. All such gen.
eral storms pass out from this country to
the Atlantic. through the st. Lawrence
valley. Within recent years these Ameri-
can storms have been actually traced
across the Atlantic to Europe, and some
Of them even as far as Asia.
IAN storms originate in the same way,
whether on land or at sea; in summer or
IN winter. The undercurrent of air
which rises need not necessarily he warm
10 make II rise: As, for instance. where
the temperature Is below the freezing
point: but the "undercurrent must lie Of
a higher temperature than that above
and surrounding it to force it TO rise. In
other words. a storm is originated by a
commingling Of unequal atmospheric
temperatures New York Commercial
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